QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Pant, K. C. Articles by Harper, A. E. Search for Related Content PubMed PubMed Citation Articles by Pant, K. C. Articles by Harper, A. E.

Food Selection Studies of Rats Fed Tryptophan-imbalanced Diets with or without Niacin¹

Department of Physiological Sciences, University of California, Davis, California 95616 and Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706

Rats given a choice between an imbalanced diet (7.8% amino acid mixture lacking tryptophan added to an 8% casein diet adequate in niacin) and a protein-free diet consistently rejected the imbalanced diet and ate mainly the protein-free diet, a behavioral pattern similar to that of rats offered a choice between other amino acid-imbalanced diets and a protein-free diet. However, when a choice was given between a diet with a tryptophan imbalance, induced by the addition of 0.18 to 0.8% threonine to a niacin-free 8% casein diet (amino acid-induced niacin deficiency) and a protein-free diet the rats did not show any aversion to the imbalanced diet, but continued to eat it until they developed deficiency signs typical of niacin deficiency. Only tryptophan would reverse the choice in the first situation above, whereas either niacin or tryptophan would improve growth and prevent the deficiency symptoms of the latter group. These results suggest that two different metabolic responses occur with the two types of tryptophan-imbalanced diets. From these and other growth and choice studies it appears that the superior nutritional quality of a diet, per se, is not enough to insure the selection of the nutritionally superior diet. That is, the choice which satisfies the metabolic need (response) or is selected in response to a need to restore homeostatis may or may not coincide with the nutritionally superior diet. Although rats choose a tryptophan-corrected diet (adequate in niacin) over the niacin-adequate, tryptophan-imbalanced diet, there is little evidence that rats are capable of choosing a diet adequate in niacin if there are no other differences in the diet.

KEY WORDS: • food selection • tryptophan imbalance • niacin deficiency

¹ Supported in part by Public Health Service Research Grants no. AM-11066 and AM-10747. A protion of this work was done as part of a Ph.D. thesis in absentia from Department of Nutrition and Food Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts.

² Present address: National Institute of Nutrition, Jamai-Osmania, Hyderabad 7, India.

Manuscript received 9 September 1971.